Monophyly of Endosymbiont Containing Trypanosomatids: Phylogeny versus Taxonomy

Abstract

To obtain additional information on the phylogenetic relationships within the family Trypanosomatidae (order Kinetoplastida), we have sequenced the small subunit ribosomal RNA genes from the endosymbiont containing species Herpetomonas roitmani TCC080, Herpetomonas sp. TCC263, Crithidia oncopelti ATCC 12982 and a partial large subunit rRNA gene from H. roitmani. The small subunit sequences in the two isolates of Herpetomonas are very similar but not identical, and so are their restriction digest profiles of kinetoplast DNA. The size of minicircles in both isolates is 4.2 kilobases. The inferred ribosomal RNA phylogenetic trees shows the genera Herpetomonas and Crithidia as polyphyletic. Endosymbiont-bearing herpetomonads cluster with the endosymbiont-bearing crithidias and a blastocrithidia to form a monophyletic clade, whereas the endosymbiont-free members of these genera are found elsewhere in the tree. These data support the hypothesis of a monophyletic origin of endosymbiosis in trypanosomatid evolution and also suggest that a taxonomic revision is needed in order to better describe the natural affinities in this family.

Selective recovery of the cultivation-prone components from mixed trypanosomatid infections: a case of several novel species isolated from Neotropical Heteroptera

“…TCC263. While it is possible that C. deanei and both strains of Herpetomonas are in fact close relatives, as also suggested independently by the same size of their unusually large size (~4.2 kb) kinetoplast DNA minicircles (Hollar et al, 1998;Brandão et al, 2000), this group does not include endosymbiontbearing C. oncopelti by any molecular criteria. Hence the apoendosymbiontic 'C.…”

“…The trees were rooted using the sequences of Bodo saltans, the closest known outgroup to Trypanosomatidae (Doležel et al, 2000;Simpson et al, 2000). Besides the maximally fully represented 'SE' clade, the analyses included other known major clades of the Trypanosomatidae, each represented by a few relatively slowly evolving members (Hollar et al, 1998;Lukeš et al, 1997;Merzlyak et al, 2001). The overall tree topologies (Figs 4 and 5) were similar to those in previous phylogenetic analyses (Yurchenko et al, 2006a(Yurchenko et al, , b, 2008 and are not discussed herein.…”

Insect trypanosomatids: the need to know more

“…The 'favourite' and most wellstudied are cultures of C. fasciculata and C. oncopelti. But, problems with these are apparent; since several Crithidia have been removed from the genus Crithidia to a monophyletic clade of symbiont bearing tryps , Hollar et al 1998, C. fasciculata is left as the only representative for the whole genus Crithidia on the rRNA tree. However, the figure from the original description of C. fasciculata L. Leger (1902) depicted epimastigotes among other cells -this fact casts some doubts on its identity and raises the possibility of mixed infection (Podlipaev 1990).…”

Phylogeny of the kinetoplastida: taxonomic problems and insights into the evolution of parasitism

“…The updated trypanosomatid tree published in 1998 was composed of five major clades (Hollar et al 1998). Only two of them, the clade of Trypanosoma and the clade of Phytomonas, represented examples of consistency between phylogeny and taxonomy.…”

“…With the progress of molecular biological studies of kinetoplastids it has become increasingly clear that existing taxonomy does not reflect the true genetic affinities in these organisms, calling for the application of molecular phylogenetic methods (McGhee & Cosgrove 1980, Camargo et al 1982, Wallace et al 1983, Podlipaev et al 1991, Dollet 1994, Vickerman 1994, Podlipaev & Lobanov 1996, Hollar et al 1998, Wright et al 1999. The phylogenetic tree can also be used as a framework to study the origin and evolution of parasitism and a number of unique molecular and biochemical mechanisms seen in this group, such as the kinetoplast DNA networks, uridylate-insertional/deletional type of RNA editing, tRNA importation in the mitochondrion, antigenic variation and the others (recently reviewed in Donelson et al 1999, Simpson et al 2000.…”